By Peter Gleick

Populations around the world face many severe water challenges, from scarcity to contamination, from political or violent conflict to economic disruption. As populations and economies grow, peak water pressures on existing renewable water resources also tend to grow up to the point that natural scarcity begins to constrain the options of water planners and managers. At this point, the effects of natural fluctuations in water availability in the form of extreme weather events become even more potentially disruptive than normal. In particular, droughts begin to bite deeply into human well-being.

This has been a bad few years for people exposed to droughts around the world. Even normally occurring droughts have begun to be made more severe by rising global temperatures and climate changes. A particularly severe El Niño has played an important role: droughts are typically more widespread and severe than normal during El Niño years. Indeed, precipitation variability on land is strongly controlled by the characteristics of El Niño events.

At any given time, some regions and some populations are being afflicted by droughts. Right now, however, the first four months of 2016 – and indeed, for the past year – water shortages are afflicting a large number of people, over a wide area. Here is the current state of drought around the world:

India: Parts of India, including the state of Telangana and its capital Hyderabad, are suffering the worst drought in recorded history, leading to acute drinking water shortages, depletion of major reservoirs, and crop failures. Overall, ten of India’s 29 states and 330 million people – a quarter of India’s population – have been affected in 2016 by a combination of failed rains, contaminated supplies, and water mismanagement.

The Caribbean: A severe drought in the northern part of the Caribbean, including eastern Cuba and Haiti, has led to water rationing for over four million people on multiple islands. In Haiti, the drought has persisted for three years and is contributing to hunger and worsening poverty.

South America: Brazil has been suffering from severe drought for several years now, and impacts extend to Colombia and Venezuela, which are suffering from water shortages, lost hydroelectricity, and agricultural failures. The water in Venezuela’s Guri Dam, which provides more than half of the country’s electricity in normal years, is too low to provide much energy and the country is experiencing rolling blackouts.

Southern Africa: Extensive areas of southern Africa are also experience severe drought, including Zambia, Botswana, Zimbabwe, and South Africa. South Africa suffered its driest year on record in 2015, influenced by El Niño. Urban water systems in Johannesburg are also experiencing severe difficulties in satisfying demand and Zimbabwe is facing food shortages andpotential loss of hydropower from Zambian hydroelectric plants.

Somalia, the Eastern Mediterranean: Further north in the Horn of Africa, famine could kill thousands of people this year in drought-hit Somalia, according to the United Nations, which is seeking emergency drought aid. The larger region around the eastern Mediterranean is also suffering long-term drought: a study published recently found that the period between 1998 and 2012 was likely the driest in the past 900 years and other assessments have linked this drought – which is still ongoing – to social and political unrest in the region and to long-term climate changes.

Southeast Asia/the Mekong Basin:  Drought-induced water shortages are appearing in Vietnam. The worst drought in decades in Southeast Asia has cut flows in the Mekong so much that salt water is moving up the river, damaging rice production and affecting fishing communities. In Thailand, estimates are that the drought will cut the country’s economic growth by 0.6 to 0.8 percent this year and the four largest dams in the Chao Phraya River basin hold only 14 percent of their capacity. These impacts are being worsened by record-breaking temperatures.

California: Finally, in the United States a severe multi-year drought hurt the Texas economy and then ended with historical flooding, while California has just entered the fifth year of below-normal precipitation, abnormally high temperatures, and reduced water availability. Studies identifying the influence of climate changes on the California drought have also recently been published (for example, here, here, and here), highlighting how a combination of natural variability with growing human influences may increasingly be a problem for societies struggling to deal with growing water-related challenges.

This blog was originally published on National Geographic ScienceBlogs.